DESCRIPTION (Adapted from applicants' abstract) Cystic fibrosis (CF) is one of the most extensively researched genetic and respiratory diseases as a target for gene transfer therapy development. It may also serve as an important model for gene transfer therapy of other diseases, especially other lung diseases. Long-term expression and lack of pathogenicity make adeno-associated virus cystic fibrosis transmembrane conductance regulator (AAV-CFTR) an attractive gene transfer vector for testing in CF patients. Although the applicant demonstrated that AAV mediated gene transfer of CFTR was efficient and persistent in a phase I clinical trial in the maxillary sinus of CF patients, expression was equivocal. Adequate expression is critical to effective and successful gene transfer therapy for CF. Many factors alter expression of wild type AAV and recombinant AAV vectors. Conversion of single stranded AAV DNA to double stranded forms is likely the main factor limiting expression. Adenoviral gene expression has a well characterized role in this process. Less is known about other factors including genotoxic agents that can also induce a 'permissive' cellular state and increase expression of AAV. This proposal focuses on two hypotheses related to expression of rAAV vectors: (1) Genotoxic agents and other factors known to induce a permissive cellular state for wild type AAV transcription will increase expression of AAV vectors in respiratory epithelial cells and (2) infection increases rAAV vector expression and factors reducing infection and inflammation decrease vector expression in respiratory epithelial cells. To test these hypotheses, the following studies are proposed as Specific Aims: (1) To characterize the effects of genotoxic agents, heat shock, ultraviolet radiation, and roentgen radiation on rAAV vector transduction of transformed and primary cultured airway epithelial cells of CF and non-CF origin; (2) To determine the effects of bacterial infection on rAAV vector transduction of airway epithelial cells; and (3) To determine the effects of anti-microbial agents and anti-inflammatory agents on rAAV vector transduction of infected and uninfected airway epithelial cells. Increasing expression of rAAV vectors is critical to the success of gene therapy for CF and potentially other genetic disorders, and may prove clinically important. Determining the effects of bacterial infection as well as the role of anti-microbial and anti-inflammatory agents will likely directly impact future clinical rAAV vector gene transfer therapy protocols. (End of Abstract)